Day 11: Senses: sound

Six Canadian cities by how loud they are: 9,623 hexagons of modelled road, rail and aircraft noise, from unmap's Urban Noise layer.

noise.json

Loading 9,623 hexagons of six cities

City

Listen to

Lden, the day-evening-night level, dB

Unfilled: no modelled source, not silence.Click a hexagon.

Each hexagon is about 460 m across and shaded by its modelled noise over a whole day, with the evening counted 5 dB louder and the night 10 dB louder, the measure Europe's noise maps use (Lden). Heard this way, a city draws itself in its freeways. In Calgary, Deerfoot Trail runs up the middle and Stoney Trail rings the edge; the loudest hexagon on a road is on Deerfoot Trail NE, at 71.6 dB. In Toronto, Highway 401 crosses the whole frame.

The brightest hexagons are airports. In five of the six cities the loudest hexagon is beside the runways, at 76 dB: Calgary International, Vancouver International, Pearson, Montréal-Trudeau and Jean Lesage. Edmonton International is south of the city, outside the frame, and only the tip of its contours reaches the southern edge, so Edmonton's loudest hexagon is on Calgary Trail, at 70.5 dB. Switch to Loudest source: road wins almost everywhere, rail draws thin lines along the main lines and yards, and aircraft take a fan off each runway. Commercial noise, from shops and restaurants, is never the loudest source in a hexagon this size.

Switch to At night. The WHO recommends keeping road traffic noise under 53 dB over the day and 45 dB at night. In Toronto's frame, 65% of the hexagons with a modelled level are over the day guideline and 60% over the night one; in Québec City's, 27% and 24%. Each frame is a rectangle around its city, so it takes in a different amount of suburb and countryside: Toronto's takes in Mississauga, Vaughan and Markham, and Québec City's reaches into the forest to the north. Compare cities with that in mind.

A hexagon with no colour is not silent. The model has no road, railway, flight path or business within range of it, as on Lake Ontario: 982 of the 9,623 hexagons. Click any hexagon for its levels, by source.

How it's made

One basemap and one layer. This is the whole map, minus the legend.

import { createMap } from '@unmap/sdk'

// noise.json: the coarsest band of the Urban Noise layer, one H3 hexagon (about 460 m) per row,
// for Calgary, Vancouver, Edmonton, Toronto, Montréal and Québec City. lden is the
// day-evening-night level in dB; a hexagon with no modelled source has no lden at all.
const hexes = await fetch('/noise.geojson').then((r) => r.json())

const map = createMap({ key: 'um_pk_live_...', container: '#map', style: 'muted' })

map.on('load', () => {
  map.addSource('noise', { type: 'geojson', data: hexes })
  const labels = map.getStyle().layers.find((l) => l.type === 'symbol').id
  map.addLayer({
    id: 'noise',
    type: 'fill',
    source: 'noise',
    filter: ['has', 'lden'], // no source is not silence: leave it unfilled
    paint: {
      // Five-decibel bands, as noise maps draw them, from the ground up to the site magenta.
      'fill-color': ['step', ['get', 'lden'], '#1E1C27',
        40, '#33203A', 45, '#4A2645', 50, '#6A2C55', 55, '#8F3368',
        60, '#C43A80', 65, '#FF3E9A', 70, '#FF8EC1', 75, '#FFD6E8'],
      'fill-opacity': 0.88,
    },
  }, labels) // under the place names
})

// Or skip the file: with the Urban Noise add-on, every band down to 25 m is one overlay.
// createMap({ key, container: '#map', style: 'muted', overlays: ['urban-noise'] })

The levels are unmap's Urban Noise layer, release 2026-11-10.28f32d82e125, which PickYourPlace's urban noise model produces. Road noise follows the UK's CRTN 1988 method on OpenStreetMap roads cut into pieces of at most 100 m, screened by the strongest building or barrier in the way. Calgary has the City's traffic counts and lidar building heights; the other five cities use typical volumes for each class of road and a 6 m height for any building OpenStreetMap does not give one, so towers screen like houses. Rail takes its train counts from Transport Canada's grade crossings inventory. Aircraft noise comes from the City of Calgary's noise exposure forecast contours, from the regulation map of Edmonton International's vicinity protection area, and in the other four cities from a model of the runways fitted to Calgary's contours. This page draws the layer's coarsest band: each hexagon's level is the median of the 343 hexagons of about 25 m inside it, and its loudest source is the most common one among them. The finer bands are the add-on's. Nothing has calibrated the model against measurements yet. Against Toronto's published measurements it reads 3 to 6 dB low by type of road, and it has no background floor, so a hexagon far from every source can read under 30 dB, quieter than any real city. It is a screening map, not a measurement.

Data

Noise levels: unmap Urban Noise, release 2026-11-10.28f32d82e125, modelled by PickYourPlace. ODbL 1.0, derived from OpenStreetMap, © OpenStreetMap contributors.
Other model inputs, each under its own licence: City of Calgary (traffic volumes, 3D buildings, rail, noise exposure forecast contours, business licences), Natural Resources Canada (building footprints), Transport Canada (grade crossings and train counts), Government of Alberta (highway traffic volumes), the Cities of Edmonton, Vancouver and Toronto (business licences), © Alberta King's Printer (Edmonton airport contours), and Copernicus DEM GLO-30 (© DLR e.V. 2010-2014 and © Airbus Defence and Space GmbH 2014-2018).
Guidelines: World Health Organization, Environmental Noise Guidelines for the European Region, 2018.

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